ABSTRACT African American (AA) and Hispanic/Latinx (HL) adolescents disproportionately engage in interpersonal violence/aggression. Even after exposure to evidence- and school-based violence prevention programs, racial/ethnic (R/E) disparities in aggression persist for these populations. One factor accounting for the disparities is R/E discrimination. Three major forms of R/E discrimination-related processes occur in schools: 1) peer R/E discrimination, 2) teachers' unintentional R/E biases, and 3) R/E disproportionality in harsh discipline, all of which have been linked to R/E minority students' poor educational and behavioral outcomes. Thus, effectively preventing aggression/violence among AA and HL youth requires a comprehensive approach that addresses R/E discrimination on multiple levels in schools. Yet, research levering empirically supported ways of addressing discrimination to enhance school-based violence prevention is sorely lacking. Drawing on compelling evidence for the efficacy of diverse approaches to addressing R/E discrimination from members of the research team, an integrated multilevel discrimination intervention is proposed to target four areas.1) Reduce unintentional bias in school personnel using the prejudice-habit breaking intervention, the only intervention that has been shown experimentally to produce long-term changes in bias. 2) Reduce peer R/E discrimination using an adaption of the prejudice-habit breaking intervention for adolescents. 3) Reduce R/E disproportionality in discipline by identifying the settings and practices in the school that are the greatest drivers of the disparities and problem-solving to address these drivers. 4) Reduce teacher stress using occupational stress management. The purpose of this study is to examine the effects of integrating these R/E discrimination interventions (RED) into mental health-enhanced Positive Behavioral and Interventions Supports (PBIS-MH), an evidence-based approach to reducing aggression and other problem behavior in schools..8 middle schools will be randomly assigned to 2 years of PBIS-MH or PBIS-MH augmented to address R/E discrimination (PBIS-MH+ RED). Data will be collected from students, teachers, and parents and school records over the course of 2 years, with a subset of youth participants assessed again at 1-year follow up while they are in high school. The study will address the following novel aims: 1) Examine the effects PBIS-MH +RED on discrimination targets. 2) Examine the effects of PBIS-MH +RED on student aggressive behavior and aggression risk factors. We will also explore the extent to which R/E group and gender moderate these effects. 3) Examine the extent that discrimination targets mediate the effects of PBIS-MH +RED on aggression and aggression risk. This study addresses critical questions needed to move the field forward in the development of comprehensive evidence-based approaches to reducing aggression in AA and HL youth.